The present invention generally relates to circuit breakers or circuit-interrupters and, more particularly, concerns a new and improved construction of gas-blast switch.
Generally speaking, the gas-blast switch of the present development is of the type containing a movable contact element and a blast nozzle which is movable conjointly with the movable contact element and surrounding such movable contact element. This blast nozzle, in the cut-on position of the gas-blast switch, is closed by a stationary contact element which engages with the movable contact element. The blast nozzle, at its inlet side, is connected with a pump chamber or compartment which can be pressurized during the cut-off stroke of the gas-blast switch. This pump chamber, in turn, possesses a jacket or shell chamber-like construction and is bounded by an inner cylinder and an outer cylinder. The inner cylinder supports the movable contact element and the outer cylinder supports the blast nozzle. Both of the cylinders can be displaced by means of a stationarily supported ring-shaped pump piston.
A gas-blast switch or circuit-interrupter of the aforementioned type is known, for instance, from U.S. Pat. No. 4,139,753, granted Feb. 13, 1979. With the prior art construction of gas-blast switch there is formed at the outer cylinder, at the region of its end closer to the blast nozzle, an inwardly directed flange-like connection part which contains passages and is secured by means of the movable contact element which is threadably connected to the inner cylinder at such inner cylinder. This connection part or element constitutes the sole mechanical connection and, accordingly, must be dimensions so as to be rather large or massive in size. Since the connection part passes through the jacket-shaped pump chamber at its outlet-side end, i.e. at that end which leads to the blast nozzle, it forms at least a restriction for the flow of the extinguishing gas which is delivered from the pump chamber to the blast nozzle because of its large or massive dimensions, notwithstanding the presence of the passages. As a result, with this state-of-the-art gas-blast switch the swept capacity or volume of the pump chamber, especially however the output of the drive moving the movable components of the switch, must be dimensions to possess an adequate size so that, during a cut-off stroke, a sufficient amount of extinguishing gas possessing an adequate flow velocity is available for blowing the switching arc between the movable contact element and the stationary contact element.